Known copolymers of .omega.-perfluoroalkyl-1,2-epoxyalkane include a polyether type copolymer of an epoxide of the formula: ##STR1## wherein R.sub.f ' is C.sub.5 -C.sub.13 perfluoroalkyl with ethylene oxide, propylene oxide, epichlorohydrin, perfluoropropylene oxide, isobutylene oxide, butadiene oxide, styrene oxide, methyl glycidyl ether or allyl glycidyl ether (cf. Japanese Patent Publication No. 25361/1971), and a polyester type copolymer of an epoxide of the formula: ##STR2## wherein R.sub.f is C.sub.3 -C.sub.21 perfluoroalkyl with a cyclic acid anhydride such as succinic anhydride, maleic anhydride, phthalic anhydride, etc. (cf. Japanese Patent Publication Nos. 11324/1982 and 1325/1982). These copolymers find application as a water- and oil-repellent and a non-tackifier as well as do a homopolymer of an .omega.-perfluoroalkyl-1,2-epoxyalkane and a copolymer of two or more .omega.-perfluoroalkyl-1,2-eopxyalkanes. The latter homo- or copolymer is hardly or not soluble in various organic solvents and their application is restricted, while the former copolymers does not have such drawbacks.
Productivity of the copolymer of the .omega.-perfluoroalkyl-1,2-epoxyalkane with ethylene oxide, etc. is not good since the reactivity of the .omega.-perfluoroalkyl-1,2-epoxyalkane is much lower than that of the comonomer so that the homopolymers of the former and of the latter are formed together with the copolymer and, in order to get the desired pure copolymer, it is necessary to separate it from the homopolymer mixture. Productivity of the copolymer with the cyclic acid anhydride is better than the copolymer with ethylene oxide, etc. but poor in water- and oil-repellency or non-tackifying property.